The invention relates to a position control system for use in positioning relative to a subsea well a subsea vehicle or re-entry tool having thrusters.
During the drilling and after the completion of a subsea well or the like, heavy pieces of equipment must be lowered to the sea floor and accurately positioned over the well. Generally, prior art systems for positioning such equipment has included the use of guidelines, wire cables under tension. Such systems are complex and difficult to install. Furthermore, the guidelines are easily broken and are difficult to keep from becoming tangled. Some prior art systems have relied on the movement of the surface ship from which the equipment is suspended in order to maneuver re-entry equipment without the use of guidelines. This approach is time consuming and requires a large reentry cone at the wellhead and is not at all suitable in rough weather.